1. Field of the Invention
The present invention relates generally to closures for pressure vessels or pipes and more specifically to an actuator for a locking member for a pressure retaining closure.
2. Description of the Related Art
Closures for pressure vessels and pipes typically comprise a round door adapted to fit an aperture in the body of the vessel, pipe, or hub extending therefrom. The aperture has an inner circumferential groove for supporting a portion of a locking member. The doors have locking member(s), or portions thereof, proximate a circumferential portion of an outer surface of the door wherein the locking member is engaged to cooperate with the groove about the aperture after the door is closed and seated in the aperture. The locking members are typically comprised of a plurality of arms or blocks slidably mounted adjacent the outer periphery of the door and movable from an unlocked position to a locked position. Other configurations of locking members include arcuate or “C” shaped rings, slotted as well as segmented, that expand to a locking configuration and contract to an unlocking configuration. In an unlocked position, the locking member(s) is within the periphery of the outer surface of the door. In a locked position, a portion of the locking member(s) protrudes beyond the periphery for engagement with the circumferential groove in the aperture. Locking member(s) have load bearing surfaces that engage an external surface of the annular groove in the hub or vessel and a load bearing surface that engages a portion of the external surface of the door. When the internal surface of the door is subjected to pressure, the resultant force is transferred from the external surface of the door to the external surface of the annular groove about the aperture through the locking member(s) wherein an internal load bearing surface cooperates with the external surface of the door and an external load bearing surface cooperates with the external load bearing surface of the annular groove of the hub.
Locking member(s) are moved outward or expanded into a locking position and moved inward or contracted into an unlocking position. In a locked position, a portion of the locking member(s) extends radially beyond the external surface of the door and when in an unlocked position, the locking member(s) are entirely within the external surface of the door. Typically, the locking members are moved between a locked and unlocked position with a manually operated lever that rotates or expands and contracts the locking member(s) into locked and unlocked positions.